[P-EM28_29PM1] Magnetosphere-Ionosphere Coupling

[PEM28-12] Inversion method for estimating the helium ion density distribution in the plasmasphere based on IMAGE/EUV data

*Shin'ya NAKANO¹, Mei-ching FOK², Pontus C. BRANDT³, Tomoyuki HIGUCHI¹ (1.The Institute of Statistical Mathematics, 2.NASA Goddard Space Flight Center, 3.The Johns Hopkins University Applied Physics Laboratory)

Keywords:plasmasphere, inverse problem, magnetosphere

The plasmasphere exhibits a variety of shapes as a result of the variation in the electric field in the inner magnetosphere due to the coupling processes between the solar wind, the magnetosphere, and the ionosphere. Global imaging observations from outside the plasmasphere provide striking evidence of the variability of the plasmasphere. In particular, the EUV imager on board the IMAGE satellite obtained global EUV images of the plasmasphere, which have provided important insights into the variation of the plasmasphere. Our aim is to obtain the information on the ion density distribution for individual events rather than simply the averaged distribution from IMAGE/EUV data. For this purpose, we propose a linear inversion technique by which to estimate the helium ion density distribution. We applied this technique to a synthetic EUV image generated from a numerical model. This technique was confirmed to successfully reproduce the helium ion density that generated the synthetic EUV data. We also demonstrate how the proposed technique works for real data using real EUV images.